Tucked into Lago Gatun in the Panama Canal, Barro Colorado was once a diverse mountaintop hosting pumas, jaguars, and more than 200 avian species. Mountaintop turned island during the flooding that accompanied the creation of the Panama Canal, and the resulting ecological catastrophe resulted in the disappearance of big cats and many birds. Thus this island became an important model for studying the effects of fragmentation in tropical forests. Oregon State University’s professor and wildlife ecologist Douglas Robinson and Ph.D. student Randall Moore are some of the many scientists who are studying the rapid disappearance of birds from Barro Colorado.
Robinson and Moore tested the idea that certain tropical, understory birds can’t (or won’t) fly across water by capturing various species and tracking their ability to fly back to land from a boat. The experiment showed that “the ability to fly even short distances between habitat fragments varies dramatically and consistently among species of forest birds,” and that the birds that can’t or won’t fly from the island to the mainland are the same birds that are failing to thrive on their water-bound patch of land.
“Our work is one piece in a whole body of evidence showing that many organisms — even birds, considered the iconic organisms for mobility — often won’t cross even absurdly small gaps, like a few meters of water or narrow roads and trails,” says Moore. “It’s yet another rock in the massive and growing mountain of evidence that we need to maintain connectivity of fragmented patches of tropical forests.” The effects of fragmentation are not limited to tropical forests, however. Biogeographical islands can exist anywhere, and are often anthropogenically caused. Preserving natural spaces for animals, building “wildlife highways” to connect habitats across major roads, and even encouraging citizens to create “wild bird friendly” backyards are all things that are being done to help mitigate fragmentation.
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